Polycarbodiimide pulp and process for producing thereof

Abstract

The present invention is intended to provide a polycarbodiimide pulp improved in heat resistance, etc. and a process allowing for easy production of said polycarbodiimide pulp. The polycarbodiimide pulp of the present invention consists substantially of a polycarbodiimide represented by one of the following formula ##STR1## wherein R 1 , R 2 and R 3 each represent a lower alkyl group or a lower alkoxy group, R 4 and R 5 each represent a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X represents an oxygen atom or a methylene group.

What is claimed is: 
     
       1. A polycarbodiimide pulp consisting essentially of a polycarbodiimide represented by the following repeating units ##STR8## wherein R 1  represents a lower alkyl group or a lower alkoxy group, said polycarbodiimide having a molecular weight of at least 2000 and being in pulp-like form. 
     
     
       2. A polycarbodiimide pulp consisting essentially of a polycarbodiimide represented by the following repeating units ##STR9## wherein R 2  and R 3  each represent a lower alkyl group or a lower alkoxy group said polycarbodiimide having a molecular weight of at least 2000 and being in pulp-like form. 
     
     
       3. A polycarbodiimide pulp consisting essentially of a polycarbodiimide represented by the following repeating units ##STR10## wherein R 4  and R 5  each represent a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X represents an oxygen atom or a methylene group, said polycarbodiimide having a molecular weight of at least 2000 and being in pulp-like form. 
     
     
       4. A polycarbodiimide pulp according to any one of claims 1 to 3, which has a thermal decomposition temperature of 450° C. or above. 
     
     
       5. A process for producing a polycarbodiimide pulp, consisting essentially of polymerizing an organic diisocyanate in the presence of a carbodiimidization catalyst in an alicyclic ether as a polymerization solvent to obtain a dope containing a polycarbodiimide having an NCO content of 3% or less and then discharging the dope and a coagulating solution containing, as the main component, a poor solvent for the polycarbodiimide, through nozzle(s) to allow the dope and the coagulating solution to contact with each other to pulp the polycarbodiimide. 
     
     
       6. A process for producing a polycarbodiimide pulp, consisting essentially of polymerizing an organic diisocyanate in the presence of a carbodiimidization catalyst in an alicyclic ether as a polymerization solvent to obtain a dope containing a polycarbodiimide having an NCO content of 3% or less and then discharging the dope and a coagulating solution containing, as the main component, a poor solvent for the polycarbodiimide, through nozzle(s) into or onto a coagulating bath containing, as the main component, a poor solvent for the polycarbodiimide while allowing the dope and the coagulating solution to contact with each other, to pulp the polycarbodiimide. 
     
     
       7. A process according to claim 5 or 6, wherein the organic diisocyanate is a compound represented by the following formula ##STR11## wherein R 1  represents a lower alkyl group or a lower alkoxy group, or the following formula ##STR12## wherein R 2  and R 3  each represent a lower alkyl group or a lower alkoxy group, or the following formula ##STR13## wherein R 4  and R 5  each represent a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X represents an oxygen atom or a methylene group, or a mixture of the compounds represented by the above formulas. 
     
     
       8. A process according to claim 7, wherein the organic diisocyanate is blocked at the terminals. 
     
     
       9. A process according to claim 5 or 6, wherein the alicyclic ether is tetrahydrofuran, dioxane, tetrahydropyran or a mixture thereof. 
     
     
       10. A process according to claim 5 or 6, wherein the poor solvent for the polycarbodiimide in the coagulating solvent and/or the coagulating bath is water. 
     
     
       11. A process according to claim 5 or 6, wherein the poor solvent for the polycarbodiimide in the coagulating bath is heated. 
     
     
       12. A process according to claim 5 or 6, wherein the dope and the coagulating solution are discharged through a double-fluid nozzle. 
     
     
       13. A process according to claim 5 or 6, wherein the dope and the coagulating solution are discharged through respective single-fluid nozzles. 
     
     
       14. A process according to claim 5 or 6, wherein the dope and/or the coagulating solution is heated. 
     
     
       15. A polycarbodiimide pulp produced by the process according to claim 5 or 6.